Vacuum-tube generator system



INVENTOR HENRl CHIREIX Ja M A ORNEY 2 Sheets-Sheet 1 Filed April 5, 192

H CHlRElX VACUUM TUBE GENERATOR SYSTEM April 22, 1930.

April 22, 1930. H. CHIREIX 1,355,386

- VACUUM TUBE GENERATOR SYSTEM -Filed April 5, 1926 2 Sheets-Sheet 2 W1 lb, I

I Fly; 7

l A 1m 5 3 8 a C I g a 1 WWW 4 4 INVENTOR HENRI CHIREIX.

TTORNEY Patented Apr. 22, 1930 HENRI CI-IIREIX, F PARIS, FRANCE VACUUM-TUBE GENERATOR SYSTEM Application filed April 5, 1926, Serial No. 99,740, and in France August 10, 1925.

The present invention has as its object improvements in the production'of high frequency currents by means of triodes. plies equally well to communication by pure continuous wave or modulated continuous wave, its chief object being the improvement of the over-all efiiciency of the system ofcommunications by increasing either the efficiency of the transmitter or the constancy of the wave sent out.

The arrangements which, with this end in view, constitute the object of the present -in.

vention are the fol-lowing:

a. A practical circuit arrangement allow- 7 ing of diminishing at will the power utilized, this being accomplished in a way different from that heretofore customary.

b. An arrangement allowing of reducing considerably the dielectric losses occasioned by bad insulation as well as the effects of socalled parasitic capacities. This arrangement is particularly convenient when the chief desideratum is the production of very short waves.

0. A simple arrangement adapted to prevent shifting from one wave to another in case of coupled circuits, and to thusi-nsure stable keying with greater power and increased efficiency. 7

(Z. A simple. arrangement adapted to modulate, at constant frequency, the transmission from a tube-equipped station, said modulation being regulated in a simple manner to the note that is desired.

6. An arrangement specially adapted to very short modulated waves and intended to avoid the variations in frequency generally occasioned by and associated with the modulation itself.

f. A symmetrical arrangement especially adapted to vary short waves and to tubes worked with a plate cooled by circulating water or oil. r

The invention may be best understood by 45 reference to the accompanying drawings which illustrate the invention as applied to several different types of radio circuits and in which Fig. 1 shows a simple circuit diagram illus- .50 trating one feature of the invention.

It ap.

Fig. 2 shows a group ofcurves illustrating the effect of the invention on parasitic capacities and losses.

3 shows a complete transmitting systern according to'the invention.

Fig. t shows a circuit arrangement according to the invention for obtaining constant output frequency in spite of changing voltage on the plate and Fig. 5 shows a symmetrical arrangement according to the invention particularly adapted to the production of very short wave lengths.

In Fig. is shown at 3 havin its filamentcurrent supplied by the source 2, conventionally represented as a :battery, and its plate voltage sup plied by the source 1, conventionally represented as a direct current generator.- The source 1 has one of its terminals grounded as at 9 and its other terminal connected to the :plate of the triode through the choke coil 4. The filament of the triode is connected to ground at 9. An oscillatory circuit comprising a condenser 6 and inductance 7 is connected between the plate and grid, the circuit including the usual blocking condenser 5"to prevent short circuiting. of the source -1, and a shunted condenser 8-:to impart the proper negative bias to the grid; The filament is connected by a variable connection 12 to the inductance? This arrangement causes the triode 3 to oscillate in a well known manner as a self-excited generator of high frequency oscillations whose frequency is determined by the electrical constants of the oscillatory circuit 6-7. V r

It will be noted, thatthis system differs from the usual circuit arrangements in that the inductance coil 4 is variable by means of the movable contact 18; hence,it will be understood-that by moving the contact in the direction of source 1, the high frequency potential across the terminals of the oscillation circuit 67 isdiminished, because the end next to the plateis subject to the full high frequency potential developed in the selfindu'ctance coil, whereas the other endis at ground potential with respect to the high frequency. Hence, the power expended in 1 a self excited triode oscillator the oscillation circuit is reduced by moving the mobile contact in the direction of the source.

It will be evident that, without departing from the spirit of the invention, self-inductance coil 4: could be replaced by two inductance coils of the variable-coupling kind known as a variometer so as to be able to vary the potential applied to circuit 67 gradually.

Fig. 1 also discloses a constant inductance coil 10 included in the filament heating circuit and a variable tap 11 connected between the grounded side of source 1 and the coil 7. The grounding point is governed by the position of the variable tap relative to the-inductance coil 7. When variable tap 11 coincides with tap 12, the filament is grounded from a high frequency viewpoint, and the plate oscillates at high potential. Under th1s condition, the parasitic capacity 1a of the plate with reference to ground (indicated by broken lines) tends to increase the wavelength. This capacity is particularly high when the waves are of very short length, and when the plate 'is cooled by the circulation of water or ofoil. On the other hand, when tap 11 is placed at the end of the. self-inductance coil joined with the condenser 5 which is generally of high capacity, the plate is at ground potential from the high frequency view point; but the filament, as will be noted, is then at a high potential which is absorbed by the inductances 10 and 7.. It will be quite evident that under these conditions the parasitic capacity 14 does not come into play at all, while the parasitic capacity 15, which was absent when taps 11 and 12 coincided, now exerts an influence.

The points set forth with reference to the parasitic capacities are equally true of the losses. Especially in the case of tubes provided with water circulation the dielectric losses due to faultyinsulation of the conduit, to the water itself, the insulation materials usedfor the vat, etc., in other words, the capacities indicated by the broken lines 14: and 15, are capacities due to imperfect dielectric material. V

In Fig. 2 are plotted the difierent positions of tap 11 along self-inductance coil 7 as abscissae againstthe wave-length (curve a) determined experimentally and the circuit losses (curve 6) as ordinates, all other things being equal. These graphs go to show that there is an optimum point which naturally depends upon the value of the parasitic capacities and the value of the dielectric losses, at which point either the losses or the para sitic capacities are reduced to a minimum. The position of the two minimum points, as

will be noted, difiers but little. It should be understood that in this case also the armature or plates ofcondenser 5 connected to the plateof the triode can readily be taken 0E cillations.

always arranged above the tap 11.

at a variable point of the self-inductance coil 4.

It will be understood that the arrangements explained above can likewise be applied to the circuits of triode tubes playing only the part of high frequency amplifiers, in other words, in circuits in which there exists no reactive coupling between grid and plate.

Fig. 3 shows a simple arrangement adapted to increase the stability of the waves given off and the efficiency in a tube-equipped transmitting station in which the antenna is indirectly excited. The same reference numerals are used to denote the same elements, in fact, the diagram in Fig. '3 differs from that in Fig. 1 only in that an antenna inductance coil 13 has been added for the object of tuning the antenna 14. The portion of the self-inductance 7 located between tap 11 and tap 16 constitutes the inductive coupling with the antenna. The portion comprised between tap 12 and tap 17 constitutes the grid reaction for the maintenance of os- In the arrangements heretofore customary, the reaction is disposed in the oscillation circuit, in other words, ta 17 is ut the present invention consists in providing the reaction in whole or in part in the antenna circuit according to whether the tap 12 coincides with tap 11 or whether it is located above tap 1'1. V

According to the theory advanced for the phenomenon designated by the German word Ziehen, the condition of oscillation in cases where the gridrreaction is provided in the antenna circuit is satisfied only for one wave. It is thus feasible to insure higher stability, more power in keying, and higher efficiency by virtue of the fact that closer coupling is feasible, .or else it is possible to tune more sharply the antenna circuittothe oscillation generating circuit. No matter which method ulated by acoustic frequency, or waves modulated at speech frequency. A very simple way of obtaining waves modulated at acoustic frequency consists in causing the plate and grid circuits of speech modulator tubes to react so as'to generate directly in the circuits of this tube-currents of musical frequency.

The frequency of a triode self-generator station depends upon the electric characteristics or constants of the circuits and, to a certain extent, upon the potentials of the tial applied to the grid and is a defect and inconvenience very undesirable in reception inasmuch as it limits the chances of tuning. Conditions can be remedied by various means; two of Which only shall be cited here by way of example. If the plate potential is supplied from an alternator, eitherin series or not in series with a high-potential direct current, it suffices to provide in the grid circuit in series with the grid reactance, a transformer fed from the same alternator. In the presence of a convenient value and phase of this supplementary potential, it is possible to neutralize, or at least reduce conveniently, the amplitude of the frequency variation. It is evidently also feasible to use a saturated inductance coil in the generator circuit in order to counteract the variation occasioned by the inconstant supply potential.

Fig. 4 shows one Way of carrying this i scheme into practice, the same comprising the two arrangements hereinbefore referred to, although it will be understood that only one of them is required. Referring to Fig. 4, 1 and 1 denote the variable high-potential source (in certain cases 1 can be dispensed with entirely) 2 is the low-potential source needed for feeding the filament of triode 3; 4 is the choke coil and 5 the blocking condenser. 6 and 7 are theelements of the oscillation circuit and 8 the usual shunted condenser. 10 denotes the transformer and 11 the saturated inductance coil (in diagrammatic form) being the object of the present invention. These two elements are supplied by means of transformer 18 from alternator l.

19, 20, 21 denote, respectively, an inductance coil, a resistance, and a condenser adapted, if desired, to provide convenient phase for the potentials or the currents to be applied to 10 z and 11. 22 finally represents a battery adapted to superpose on the saturated inductance coil a certain direct current upon the alternating current furnished from transformer 8. It Will be noted that with one of these two ele ments 10 or 11 it is possible to balance the variations introduced by the fact that the plate potential is subject to periodical variations.

In the light of What has been pointed out With respect to Figs. 1 and 2 it has been found that the asymmetrical arrangement illustrated in Fig. '5.-is particularly :adapted 'to thep'roductionof very short waves, especiallywhen tubes of the wateror oil-cooled type :are used.

It will be easily understood that the plates of t-riodes, looked at from the viewpoint of high frequency, are at ground potential, and that,as a consequence, the parasitic capacities with reference to the ground of these :platesor the metallic paths surrounding them willno longer interfere another zpointis that,

.as explained above, the losses :are -greatly diminished. 1n this-arrangement, land 2 stand for thecsources, 3 a p21 1I' Of'tIl0Cl6S,4 the selfinductances of the oscillation circuit, 5 the condenser connected between acommonlpoiint of the anode'and the earth, 8 the grid shunt condensers, 6 and 7 a capacity'and a selfinductance coil additionally provided, :according to. whether the lengthof the wave sent out is tobe increased or decreased.

l/Vheh 6 or 7 are -omitted,oscillations will be started by action merelyof the capacity of coils 4 and the capacities of the triodes V WVhen the supplementary self-inductance coil 7 is tuned with the capacities of tri'odes 3 connected in series, each ofthecoils .4 will oscillate quarter-wave fashion, the glldS at every lnstant belng-atpotentials opposed with relation to theground potential. If thesymmetry is perfect, it is unnecessary "to provide choke coils in series with sources 1 and 2.

Having described my invention, I claim:

1. A circuit arrangement comprising a,

vacuum tube oscillator, a source of energy for supplying plate voltage thereto having one of its terminals connected to the plate through an inductance, an impedance having one of its terminals connected to said inductance by a variable contact and its other terminal connected to the grid of said oscillator and a variable contact connected to the filament of said oscillator and contacting with said impedance.

2. A circuit arrangement comprising a vacuum tube oscillator, a source of energy for supplying plate voltage thereto having one of its terminals connected to the plate through an inductance, an oscillatory circuit comprising an inductance and a capacity in parallel connected to said first mentioned inductance through a variable contact and to the grid of said oscillator, and a variable contact connected to the filament of said oscillator and contacting with the inductance of said oscillatory circuit.

3. In a tube generator circuit arrangement including an oscillation circuit, means for reducing the 1085% due to imperfect dielectries and the effect of stray capacities, comprising means for feeding the filament of the tube generator through the self-inductance coil of the oscillation circuit, a connection to ground of the filament feeding means,

to earth that losses due to bad dielectrics and Y the influence of parasitic capacities are reduced and the frequency of the'emitted Wave stabilized. V

5. A thermionic valve generator circuit, comprising an oscillatory circuit connected between plate and grid electrodes, a filament heating source connected to ground,'the filament heating circuit including a portion of the inductance forming a part of said oscillatory circuit, and an adjustable ground connection to an intermediate point of said inductance, whereby the high frequency potentials of the difierent electrodes are so defined with respect to earth that losses due to bad dielectrics and the influence of parasitic capacities are reduced and the frequency of the emitted Wave stabilized.

HENRI OHIREIX. 

